Der einfluß von temperaturänderungen auf den Ionen- und Wassergehalt in blutplasma und geweben von Tinca tinca

Two-year old Tinca tinca L. (previously acclimated for at least 3 weeks to defined temperatures) were subjected to slow (24 h) and fast (2 h) temperature changes from 13.5° to 26°C (observational period 504 h) and from 6° to 16°C and vice versa (observational period 288 h). Effects on coefficient of condition, Na, K, Ca and Cl content of plasma, H₂O, Na and K content of muscle and liver, and rates of movements of gill-covers, when the temperature rose to 26°C, were recorded. After temperature change from 13.5° to 26°C, sharp increases occur in the amount of K and Cl in the blood plasma, of H₂O in the liver and, if the temperature rise is effected quickly, of muscle H₂O content. Substantial reductions were recorded in coefficient of condition and K content of the liver. With a fast rise in temperature, liver Na content decreases sharply at first, but rises again later. After temperature change from 6° to 16°C, Ca increase in blood plasma and (if the temperature is raised slowly), decline in muscle Na content are considerable; drop of liver H₂O content is less marked. If the temperature change is effected rapidly, then liver Na content and plasma K diminish initially and, thereafter, rise sharply. In the case of quick temperature change from 16° to 6°C, particularly frequent and marked changes in ion and water contents occur; in most cases adjustment is not complete after 288 h, and the observed variations are often clearly different from those observed in the case of slow temperature change. If temperature is lowered rapidly, the amounts of Na and K in muscle and liver fall and the amount of H₂O increases. There is a considerable loss of Na and Cl contents and, after rapid temperature change, also in plasmatic K and Ca contents. The responses of fishes acclimated to 6° and 16°C are compared; at 16°C the coefficient of condition and plasmatic Na, K and Cl contents decrease, and H₂O, Na and K contents of the liver increase. The amount of K in the plasma and of H₂O, Na and K in the muscle remains unchanged. The stress effect upon ion and water contents during transfer to 6°C is significantly greater during fast than during slow temperature change. The problem of proper differentiation between biological consequences of stress and adaptation phenomena is discussed. Complete adaptation was frequently not attained during the course of our experiments, especially not at low temperatures.